Failure to find broken "current" links

Last week we ran a full documentation build with the --rebuild option against https://github.com/elastic/docs/pull/934.
It succeeded with no broken links.
However, when the PR was merged, the doc builds failed with this error:

> 07:45:13 INFO:build_docs:Bad cross-document links:
> 07:45:13 INFO:build_docs: /tmp/docsbuild/target_repo/html/en/cloud-enterprise/1.0/ece-change-user-settings.html:
> 07:45:13 INFO:build_docs: - en/elasticsearch/painless/current/painless-examples.html

The destination page had changed a month ago (https://github.com/elastic/elasticsearch/blame/7.2/docs/painless/painless-guide/painless-walkthrough.asciidoc), so if the link check was using the appropriate local "current" folder, we would have expected it to find this problem.